Effect of Fluorocitrate Administered Intrathecally on Mechanical and Heathyperalgesia Induced by Chronic Constriction Injury of Sciatic Nerve in Rats

Objective To observe the effect of fluorocitrate,a glial inhibitor,administered intrathecally on thermal withdrawal latency(TWL) and mechanical withdrawal threshold(MWT) of rats with chronic constriction injury(CCI) of the sciatic nerve. Methods SD rats in all groups were intrathecally cathetered at 8 d before operation.Mechanical allodynia and heat hyperalgesia were evaluated by MWT and TWL,respectively.For the rats receiving pre-treatment,glial inhibitor fluorocitrate(50 ug) or normal saline(10 ul),beginning on 1 d before operation,were intrathecally administered twice daily for consecutive 3 days(pre-treatment),the values of TWL and MWT were measured prior to sciatic nerve ligation and at 1,3,5,7,and 14 d after surgery.For the rats receiving post-treatment,fluorocitrate(50 ug) or normal saline(10 ul) were intrathecally administered once on the seventh day after ligation,the values of TWL and MWT were examined at 0.5,1,2,4,and 8 h after intrathecal injection. Results In pre-treatment group,there was significantly increasing in MWT and TWL in group receiving fluorocitrate from day 1 to day 5 post ligation(P0.05,P0.01).As compared with those at different time points in post-treatment group receiving normal saline,the MWT and TWL in group receiving fluorocitrate significantly increased at 0.5,1,2,and 4 h post drug(P0.05,P0.01). Conclusions Intrathecal treatment with fluorocitrate significantly delays the occurrence of thermal hyperalgesia and allodynia or suppresses the established thermal hyperalgesia and allodynia in CCI rats.The results suggest that glial activation is involved in the forming and maintenance of neuropathic pain induced by CCI.